It is well known to use spas, also commonly referred to as hot tubs, outdoors during cold weather seasons to provide an enjoyable experience using the contrast of the cold ambient outdoor temperature and the heated water of the spa. However, a known problem with winter use of an outdoor spa is that if power is cut off to the water circulating pump and heater of the spa, the water in the tub and in the pipework connected thereto can easily freeze if ambient conditions are cold enough, and the expansion of the water as it freezes can cause cracks to form in the tub or pipes, which can lead to leaks when the water thaws and can require costly or time consuming repair or replacement of components or entire systems.
The powered components of a spa include a water heater, at least one pump for circulating water through pipes interconnecting the heater and the tub, and a controller operable to control the pump and the heater in response to input from an owner, operator or user of the spa. Collectively, these components are often referred to as a spa pack. The spa pack is typically connected to a power source through a ground fault circuit interrupter (GFCI), which will disconnect electrical communication between the spa pack and the power source if a ground fault is detected in order to remove a potential electrocution hazard. This is problematic during winter use of the spa, in that if the GFCI cuts off the power supply to the spa pack and the hot tub is left unattended, the water can quickly freeze, especially in the circulation pipes, and cause damage to the spa. Operating spas are sometimes left unattended for extended periods of time during the cold weather season, for example by cottage owners who transit back and forth between a rural cottage and an urban environment and leave their cottage spa running between visits during the winter season to prevent freezing. Should the GFCI trip in their absence, they will likely return to find their spa frozen when the next retreat to the cottage.
Accordingly, it is desirable to provide freeze protection for spas suing ground fault protected spa packs.